Why is there an F# in the Aminor 13th chord please?

Hello everyone

I have looked up the spelling of an A minor 13th: A - C – E - G (dominant 7th) - B- D -F#. Yet the 13th, the F is not
sharpened in the key of A minor (Harmonic version of the scale,)

Why F#?

I’m going wrong somewhere- can’t work it out.

Regards

Anybody? Please?

Righto then.

Hi; to put it very broadly, the reason for augmented 13th is that otherwise it would make an (perfect) 4th interval to the minor 3rd: that is, C-F; this interval would yield a weakened relation regarding the tonal (minor) centre, that is, A-E. By augmenting F, the A minor chord gets a dissonant interval within , a tritone interval (augmented fourth): C-F#, so in this case the chord inherits a dissonance comparable to, ley's say, a major-7th; therefore, enabling the analysis of the extended chord as in the case of, say, an either minor on major seventh chord. So some questions arise: what is the effect of going onto a Maj7 chord instead of going onto a perfect one; for instance, say, going from CMajor onto FMaj7 vs from CMajor onto FMajor (perfect)? Greetings



Edited 2 time(s). Last edit at 07/02/2022 08:34AM by Athair. (view changes)

Hello Athair.

Your explanation needed me to try it all out on the keyboard and it's all clear to me now.

Many thanks, keep well.

Alan

Re: Why is there an F# in the Aminor 13th chord please.

I sent you a private message as the computer thinks my message is a bot.

Regards

Alan

Glad to know it helped! Keep making questions as you find doubts around some subject; from time to time is worthwhile trying to manage so as to come with some explanation about something; greetings!

Thank you.
Alan